Bion 2 was a Bion

Bion (satellite)

The Bion satellites or Bion space program , also named Biocosmos, were a series of Soviet biosatellites. They were part of the Cosmos satellites....

 satellite launched by the Soviet Union

Soviet Union

The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 on October 22, 1974 at 1800 hours UTC. It carried albino rats for biomedical research

Biomedical research

Biomedical research , in general simply known as medical research, is the basic research, applied research, or translational research conducted to aid and support the body of knowledge in the field of medicine...

. Soviet, Czechoslovak

Czechoslovakia

Czechoslovakia or Czecho-Slovakia was a sovereign state in Central Europe which existed from October 1918, when it declared its independence from the Austro-Hungarian Empire, until 1992...

, and Romania

Romania

Romania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...

n scientists subjected the rats to daily radiation doses from a gamma source by ground command. When they were recovered 20.5 days later, many rats had developed lung problems and their blood and bone marrow had changed more than those of control specimens. It had an on-orbit dry mass of 5500 kilograms and had a US National Space Science Data Centre ID of 1974-080A.

The spacecraft was based on the Zenit spy satellite

Zenit spy satellite

Zenit is the name of a series of military spy satellites launched by the Soviet Union between 1961 and 1994. To conceal their nature, all flights were given the public Kosmos designation...

with emphasis on studying the problems of radiation effects on human beings.

It was also known as Biocosmos 2, Cosmos 690 and 07478